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How the Horizon H-racer Works


Powering the H-racer
The H-racer connects to a refueling hose.
The H-racer connects to a refueling hose.
Photo courtesy of Horizon

The 6-inch-long (15-centimeter) H-racer is actually a lot like the kind of full-size hydrogen-powered car you'd find at an auto show. Inside is a PEM fuel cell, the type that powers cars like the Honda FCX Clarity concept (which is actually being driven by some lucky Californians).

A PEM (proton-exchange membrane) fuel cell is kind of like a battery. There's an anode (hydrogen), a cathode (oxygen), an ion-exchange barrier (the membrane), and a wire circuit that connects the anode and cathode so electrons have a place to flow. Hydrogen molecules in the anode react with a catalyst, breaking them into electrons and hydrogen protons. The electrons travel across the wire to the positively charged cathode, creating an electrical current, and the protons cross the proton-exchange membrane. Once in the cathode, the hydrogen protons and electrons react with atmospheric oxygen, creating water.

That's the basic process, anyway (see How Fuel Cells Work for a complete explanation). The big question is: Where does the hydrogen fuel come from? That's one of the obstacles to large-scale hydrogen power -- how to generate hydrogen gas cleanly and efficiently. In the H-racer, the feat is accomplished using water and electricity.

Solar electricity, to be exact.

Powering up the H-racer goes like this:

  1. Insert the refueling hose into H-racer's gas tank.
  2. Pour water into the hydrogen refueling station and activate the solar panel (if it's not sunny, you can still play -- just insert a couple of batteries).
  3. The solar panel generates an electric charge and applies it to the water, resulting in electrolysis. The water splits into hydrogen molecules (H2) and oxygen molecules (O).
  4. The refueling station releases the oxygen into the air and sends the hydrogen to the H-racer via the hose, where it enters the car's PEM fuel cell.
  5. In the fuel cell, the hydrogen generates an electrical current and recombines with oxygen from the air. The car releases the resulting water vapor.
  6. H-racer is ready to drive.

Using one tank of hydrogen, H-racer 2.0 can drive about 100 meters (328 feet) at approximately 25 meters per minute, which is faster than the original model thanks to a more efficient fuel cell [source: Arbor]. That gives you about four minutes of driving before you refuel. The fuel cell also powers the LEDs that give the car its neon glow.

Since refueling is pretty much the point with this particular model car, the four-minute tank isn't really a drawback. But it highlights some of the complex issues facing hydrogen implementation in real cars. A system this clean and simple doesn't exactly translate.

So does something like H-racer really affect the progress toward hydrogen-powered cars?


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